The present invention relates to a door assembly for a heating, ventilation, and air conditioning (HVAC) system in a vehicle and a method for making the same.
In a typical vehicle heating, ventilation, and air conditioning system (HVAC) system, a heater core is mounted in an air duct downstream of an evaporator core. Hot engine coolant is circulated through the heater core to heat air directed through the heater core. For air conditioning, a refrigerant is circulated through the evaporator core to cool air directed through the evaporator core. Control of the air temperature is obtained by controlling the flow of air from the evaporator core into the heater core. For maximum cooling, all of the air flow from the evaporator core bypasses the heater core and travels through a chamber and into the passenger compartment. Alternatively, for maximum heating, all of the air flow from an inactive evaporator core passes through the heater core, where the air is heated, before traveling through the chamber and into the passenger compartment. Intermediate these two extremes, bypass (cold) air flow and air flow through the heater core are mixed in the chamber to provide air into the passenger compartment at intermediate temperatures.
Many of the components of the HVAC system, such as the heater core, the evaporator core, the ducting, and the chamber described above, are located in the vehicle instrumental panel. Physical space in the vehicle instrument panel has historically been limited, and is even more limited today as new electronic devices and convenience features are being added to the instrument panel. Consequently, the volume of space in the instrument panel that is taken up by the HVAC system must be minimized.
Minimizing the space taken up by the HVAC system in the instrument panel includes minimizing the space taken up by a plenum that directs the air out into the passenger compartment through various ducts, such as instrument panel ducts, front rear seat floor ducts, and defroster ducts. One or more doors are typically mounted in the plenum and are movable between multiple positions to direct the air from the HVAC system through one or more of the aforementioned ducts. In the interest of saving space in the instrument panel, as well as time and cost during manufacture, it is desirable to simplify the construction of the doors.
The present invention is a door assembly for use in a heating, ventilation, and air conditioning system in a vehicle. The door assembly comprises a rotatable shaft made of a first polymeric material and having an axis about which the shaft rotates. A first door projects radially from the first shaft. The first door is made of the first polymeric material and is molded together with the shaft as a continuous, unitary part so that the first door is rotatable about the axis. A rotatable sleeve is made of a second polymeric material that has a lower melting point than the first polymeric material to enable the sleeve to be molded over the shaft. The sleeve is disposed coaxially about the shaft and is rotatable about the axis relative to the shaft. A second door projects radially from the sleeve. The second door is made of the second polymeric material and is molded together with the sleeve as a continuous, unitary component so that the second door is rotatable about the axis relative to the first door.
In accordance with another aspect, the present invention is an apparatus for a heating, ventilation, and air conditioning system that provides air at a controlled temperature into a passenger compartment in a vehicle. The apparatus comprises a housing having a chamber. The housing defines at least one inlet through which air flows into the chamber. The housing further defines at least two outlets for directing air flow out of the chamber. A door assembly is disposed in the chamber. The door assembly comprises a rotatable shaft made of a first polymeric material and having an axis about which the shaft rotates, and a first door projecting radially from the first shaft the first door being made of the first polymeric material. The first door and the shaft comprise a continuous, one-piece, unitary part so that the first door is rotatable about the axis with the shaft. The first door is movable to at least partially block air flow out of one of the at least two outlets. The door assembly further comprises a rotatable sleeve made of a second polymeric material that has a lower melting point than the first polymeric material to enable the sleeve to be molded over the shaft. The sleeve is disposed coaxially about the shaft and is rotatable about the axis relative to the shaft. A second door projects radially from the sleeve. The second door is made of the second polymeric material. The second door and the sleeve comprise a continuous, one-piece, unitary component so that the second door is rotatable about the axis relative to the first door. The second door is movable to block air flow out of the one of the at least two outlets.
The present invention further includes a method for providing a door assembly for a heating, ventilation, and air conditioning system. According to the inventive method a first component comprising a first door and a shaft is molded out of a first polymeric material having a first melting point. The first door projects radially from the shaft and is rotatable along with the shaft about an axis. A second component is then overmolded about the first component. The second component is made of a second polymeric material having a second melting point that is lower than the first melting point of the first polymeric material. The second component comprises a second door projecting radially from a sleeve that is coaxially disposed about the shaft and is rotatable relative to the shaft.